To investigate the change of conformation of ATP and with it the energy storage and release when it is bound to the arginine and lysine residues of actin, CNDO/2 MO calculations of these systems are in progress. Using different semiempirical methods, a useful correlation has been established between an electronic index and the pharmacological activity of a series of substituted benzylamines. Ab initio MO investigation of the possibility of charge transfer between -S- containing model compounds as donors and model compounds of a polypeptide chain (as acceptors) are in progress. Further new methods have been worked out to calculate the band structure of aperiodic polymers and to compute the interactions between polymer constituents. The application of these methods to biopolymers is planned.